Pityriasis rubra pilaris with symmetric polyarthralgia and lymphadenopathy

Summary: Abstract Body: Pityriasis rubra pilaris(PRP) is a rare, inflammatory cutaneous disorder of unknown etiology and its association with inflammatory joint disease has not been well established. Here, we present a case of biopsy-confirmed PRP presenting with symmetric polyarthralgia and lymphadenopathy treated with ixekizumab, an IL-17 inhibitor. The disease typically presents with follicular papules and palmoplantar keratoderma. Paraneoplastic PRP has been proposed in several case studies and presents the possibility that immunologic dysregulation or elevated growth factors due to a primary neoplasm contribute to PRP pathogenesis. The lack of definitive evidence or clear guidelines makes PRP treatment difficult. Proposed treatments include immunomodulators, acitretin, methotrexate and isotretinoin. In the case of paraneoplastic PRP, surgical excision of neoplasms can serve as treatment. Our patient presented with multiple non-melanoma skin cancers and a nonspecific erythematous, pruritic eruption on the upper back and chest. His course was complicated by arthralgias of the bilateral hands and reactive lymphadenopathy of the axillary lymph nodes. He saw slow improvement in his rash after treatment with ixekizumab. He also had an impressive response to sonidegib, with shrinking of the large BCC tumors on his back, which were subsequently excised via Mohs. One large BCC on the left neck was removed via wide local excision. Regarding treatment of the patient’s joint pain, the patient was continued on ixekizumab and started on celecoxib as needed for pain. PRP-associated arthritis is a rare component of the primarily dermatologic disorder, and it is important for clinicians to be aware of this association to adequately address joint manifestations. When applicable, paraneoplastic PRP should be explored, and underlying neoplasms should be treated. Isabella Anderson⁴, Christopher Boldt¹, Amy Le Huong², Kristin Richards³ 1. Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States. 2. Rheumatology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States. 3. Dermatology, The University of Texas MD Anderson Cancer Center, Houston, TX, United States. 4. The University of Texas Health Science Center at Houston, Houston, TX, United States. Adaptive and Auto-Immunity